2. Obligate intracellular parasite
It belongs to coccidian parasites
The name toxoplasma derived from “toxon”
arc or bow ( curved shape of the tachyzoites)
Phylum - sporozoa
4. Actively multiplying form
Crescent shaped
Seen in acute infection
Infect all the nucleated mammalian cells
Inside the host cell, the tachyzoites are
surrounded by a vacuole asexual
multiplication occurs rosettes
Host cell distends pseudocyst
7. Resting stage of the parasite
Seen in chronic infections most common
site is muscles and brain
Inside the cyst slowly multiplying
trophozoites are called as bradyzoites
BRADYZOITE:
Resistant to gastric juice
Multiplies slowly
Contains PAS positive amylopectin granules
9. Sexual form of the parasite found only in cats
and felines
12. Enteric cycle or sexual
cycle
Exo enteric cycle or
asexual cycle
15. 1. Ingestion of sporulated oocysts from
contaminated soil, food or water
2. Ingestion of tissue cyst containing
bradyzoites from undercooked meat
3. By blood transfusion, needle stick injuries,
organ transplantation
4. Transplacentral transmission
5. Laboratory accidents
( Tachyzoites are the infective form in blood)
16. A known AIDS patient presents with
complaints of fever, seizures, visual defects
and facial nerve palsy and altered sensorium.
His CD4 count is 78/ul
CT scan brain shows multiple ring enhancing
lesions in the basal ganglia
18. A newborn baby is presenting with visual
impairment, microcephaly, hydrocephaly and
on CT scan it showed intracerebral
calcification.
19. Features in immunocompetent individual
Features in immunodeficient individual
Congenital toxoplasmosis
Ocular toxoplasmosis
22. Direct microscopy Detection of
tachyzoites in blood and tissue cyst in tissue
biopsy
Staining methods:
1. Giemsa
2. PAS
3. Silver stains
4. Immunoperoxidase stain
23. Detection of Toxoplasma antigen by ELISA
Detection of Toxoplasma antibody by
1. Sabin feldman dye test
2. IgM ELISA
3. IgG ELISA
4. IgG avidity test
25. Gold standard antibody detection test
Done only in reference laboratories
Complement mediated neutralization test
that requires live tachyzoites
Live tachyzoites are incubated with
complement and test serum
Alkaline methylene blue dye is added and
reincubated
26. Toxoplasma antibodies in the serum bind to
the antigens in the live tachyzoites killed
due to complement mediated lysis
Killed tachyzoites thin, distorted and
colourless
The dilution of the test serum at which 50% of
the tachyzoites are killed antibody titer of
the test serum
27. Toxoplasma antigens in amniotic fluid
PCR
IgM antibodies in fetal blood by ELISA
Role of IgG antibodies in diagnosing
congential toxoplasmosis ?
Ultrasound of fetus at 20 to 24 weeks of
gestation
29. Toxoplasmosis in AIDS:
Cotrimoxazole
Dapsone – Pyrimethamine
Atovaquone with pyrimethamine
30. Consumption of cooked meat
Hand hygiene
Prenatal and antenatal screening to detect
Toxoplasma infection in women of child
bearing age
Proper handling of pet cats
Screening of blood donors and organ donors